Although common electrical machines have matured, there still is a demand for improvement. Companies are pushing for automotive fleet electrification for environmental reasons (e.g., global warming) and economic reasons (e.g., higher efficiencies). Engineers in numerous technical fields, such as wind turbine generators, are faced with noisy electric motors and electric machines.
For simulation, engineering, and live operation, it is favorable to obtain a direct measurement of the forces between the rotor and the stator in an electrical machine (e.g., an electric motor). In such systems, however, the conditions are not favorable for the placement of strain gauge sensors due to electromagnetic interference. In many cases, undesired holes are drilled to create space for such resistive strain gauges, which disturbs magnetic flow. Accordingly, equipping a machine with strain gauges is not ideal because the equipping disturbs the magnetic field and results in inaccurate measurements.
While the use of piezoelectric sensors may achieve a more accurate transducer immune to electromagnetic interference, the use of piezoelectric sensors is not ideal for measuring low frequencies or direct current (DC) due to creep. Moreover, piezoelectric sensors suffer from difficult signal evaluation due to non-linearities, such as hysteresis.
Currently, there are no sufficient measurement techniques available to accurately predict noise radiated by electric motors or to address the bottleneck of the electromagnetic forces acting on a stator. As a result, simulation results are not accurate. Conventional measurement techniques of placing sensors in limited spaces generally present undesired high electromagnetic interference.
Measuring indirect quantities through simulation, such as the magnetic flux and torque in the axle to reconstruct the original force values, also are inadequate because they lack precision, particularly in newly constructed machines.